Sheet metal working hammer with work cooling means



J. M. GETZ April 23, 1957 SHEET METAL WORKING HAMMER WITH WORK COOLING MEANS Filed March 3, 1953 JTTORNE $15 United States Patent SHEET METAL WORKING HAMMER WITH WORK COOLING MEANS John M. Getz, Los Angeles, Calif. Application March 3, 1953, Serial No. 340,019 1 Claim. (Cl. 8115) My invention relates to sheet metal working hammers, and more particularly to a sheet metal working hammer which is arranged to perform metal shrinking operations. Heretofore, the procedure followed to shrink sheet metal has involved heating a small area red hot, pounding the area with a hammer while backing the area with a dolly or anvil, then chilling the area with a wet or damp cloth. This requires four pieces of equipment and two workers or the worker must drop one tool and pick up another.

Bearing in mind the nature of the problem involved, the objects of my invention include:

First, to provide a sheet metal shrinking hammer which carries a water supply and causes a film of water to be applied over the area struck by the hammer so that the metal is chilled simultaneously with the impact of the hammer. Thus, by repeated blows of the hammer on the heated metal surface, the sheet metal may be caused to shrink and to assume the desired contour whether fiat or curved.

Second, to provide a hammer of this type which may incorporate a valve having an end protruding from the hammer and engageable with the surface struck by the hammer so as to open momentarily and dispense a small quantity of liquid, the valve in no way interfering with operation of the hammer.

Third, to provide a hammer of this type which is simple and economical of manufacture and dependable in operation.

With the above and other objects in view appearing hereinafter, reference is directed to the accompanying drawing.

In the drawing:

Figure 1 is a side view of my sheet metal working hammer.

Figure 2 is an enlarged sectional view through the hammer head taken along the line 22 of Figure 1.

Figure 3 is a transverse sectional view taken through 33 of Figure 2.

Figure 4 is a fragmentary view, showing the operating end of the hammer.

Figure 5 is a fragmentary sectional view similar to Figure 2, showing a modified form of my hammer.

My sheet metal working hammer includes a reservoir cylinder 1 which forms the head of the hammer. Fitted in one end of the cylinder is a disk 2 which is relatively heavy and forms the striking end of the hammer head. The disk 2 is permanently secured in place by furnace brazing or welding.

Centered in the disk 2 is a boss 3 having a central bore 4 terminating in a small conical aperture which forms a valve seat 5. The bore 4 receives a valve 6 having a conical valve tip 7 which protrudes slightly from the aperture which forms the valve seat 5. At the base of the boss 3 the bore 4 is intersected by one or more radially directed supply ports 8. Y

The outer end of the bore 4 is internally threaded and receives a screw threaded plug 9. The plug 9 is provided with a socket coaxial with the bore 4. The socket receives a spring 10 which bears against the valve 6 so that the valve normally engages the valve seat 5.

The upper end of the plug 9 may be polygonal to receive a wrench or slotted to receive a screw driver. The end of the cylinder 1 from the disk 2 is internally 2,789,453 Patented Apr. 23, 1957 ICC threaded to receive a plug 11 which may be formed of impact resistant plastic so that this end of the hammer may be used as a soft hammer. Welded or otherwise permanently attached to one side of the cylinder 1 is a handle 12 which may be provided with a suitable grip 13 at its extended end.

Operation of my hammer is as follows:

The reservoir cylinder 1 is filled with water. The surface to be worked is heated, for example, by an acetylene torch. This may be done by holding the torch in one hand while the hammer is held in the other. Actually the surface need not be heated red hot, or for that matter even to the point at which the metal discolors. In fact a metal surface heated merely by the action of a power buffing or polishing head can be shrunk by use of my hammer. When a region of the surface has been heated sufficient, it is struck repeatedly by the hammer. With each blow the valve tip 7 is moved inwardly against the action of the spring 10 so that a small quantity of water is discharged and caused to spread as a film between the hammer and the surface. This action, of course, takes place more or less instantaneously, and is aided by the transient pressure created by the de-acceleration of the water on impact of the hammer.

The water immediately evaporates and absorbs heat from the metal. This heat is relatively substantial by reason of the heat of evaporation of the water.

The sudden chilling of the metal causes it to shrink so that by repeatedly heating and striking the metal, a selected area may be controllably shrunk so as to eliminate the bulge or other departure from the desired contour.

With reference to Figure 5, the reservoir cylinder 1 is shown as provided with a striking disk 15 similar to the disk 2, except that the boss 3 is omitted, and in place of the valve means a capillary aperture 16 is provided. The aperture 16 is sufi'iciently small so that water contained in the cylinder does not readily leak out.

However, on sudden de-acceleration of the hammer on striking an object, the resultant transient pressure created in the cylinder forces a small quantity of water from the cylinder.

Having fully described my invention, it is to be understood that I do not wish to be limited to the details herein set forth, but my invention is of the full scope of the appended claim.

I claim:

A sheet metal working hammer comprising: a substantiaily cylindrical water reservoir member; a striking head closing one end of said cylinder; a filler cap closing the other end of said cylinder; a handle rigidly connected to and extending radially from said cylinder; a boss extending from said striking head into said reservoir, said boss having a central bore penetrating said striking head and terminating in a valve seat, lateral ports communicating between said bore and reservoir; a valve member slidable in said bore engageable with said valve seat and protruding from said striking head, thereby to open upon impact of said striking head with a surface to permit discharge of a droplet of water to chill said surface; and a spring in said boss backing said valve member.

References Cited in the file of this patent UNITED STATES PATENTS 521,421 Scarborough June 12, 1894 1,062,576 Baskett et al. May 20, 1913 1,318,565 Johnson Oct. 14, 1919 1,756,141 Spellmeyer Apr. 29, 1930 2,604,914 Kahlen July 29, 1952 FOREIGN PATENTS 218,840 Great Britain July 17, 1924 

